Chemicals, fertilizers and other particulates (in powder or granular form) are commonly applied to agricultural fields by a particulate distribution system that typically includes transverse spreading assemblies overlapping a swath across the field during each pass of the equipment. The particulate distribution system can be mounted on any form of land vehicle, such as a trailer, truck or specially designed self-propelled vehicle. Normally such vehicles will carry a particulates storage hopper, a transverse distributor for spreading the particulates, and a conveyor for moving particulates from within the hopper to the distributor. Because uniformity is necessary to effective spreading of chemical particulates about a field, a metering system for measuring and allocating flow of particulates spread onto the field is either included within the distribution system or is interposed between the conveyor outlet and the receiving distribution system.
One form of distribution system for spreading of particulates is a relatively simple spinner. One or more rotating spinners fling particulates onto the field surface as the material is dropped onto the spinners by a delivery mechanism or conveyor.
Mechanical delivery of particulates has been accurately achieved by mounting a transverse spreader hopper across a vehicle and providing a system of baffles, apertures, agitators and/or augers along its length. One example of such system is shown in U.S. Pat. No. 3,259,278, issued Jul. 5, 1966. A later improvement in such systems is disclosed in U.S. Pat. No. 3,680,741, issued Aug. 1, 1972. As illustrated in both patents, increased width across the distribution system was achieved by utilizing foldable hoppers that can either be arranged at the sides of a vehicle for distributing particulates at positions alongside the vehicle for transport purposes.
More recently, field application systems have been introduced which use pneumatic distribution tubes to carry particulates outwardly to each side of a vehicle. These systems are illustrated by the equipment shown in U.S. Pat. Nos. 4,462,550 and 4,964,575. In these systems, metering of incoming particulates between vertical chutes leading to the tubes is achieved by mechanically flinging the particulate material by a centrifugal deflector. Other metering systems that have been commercially used in such systems involve metering rollers, star wheels and conveyor chains.
This disclosure is applicable to any form of particulate distribution system where it is desired to apply at least two types of particulates in a uniform mixture. Such mixtures cannot always be premixed prior to delivery to the mobile spreading assembly, since vibrations and discharge of the particulates might result in stratification. Furthermore, many users (farmers) do not have equipment readily available for accurately mixing dry materials, with or without wetting, and the accuracy of pre-mixing components deteriorates as the ratio of one component to another increases. It is also desirable for the user to be able to vary the ratios of the components to match field conditions encountered at the time of application.
The desired mixtures might include two types of particulates or one or two particulates plus a liquid. The particulates and/or liquids might include fertilizers, pesticides, herbicides and other agricultural chemicals used for treating soil, growing crops and/or insects. Because the present equipment is designed for distribution of particulate solid materials, the active ingredients must be in the form of granular or wetted granular materials that can be accurately metered and conveyed by use of augers. The present system permits the user to selectively choose from two forms of particulates and a liquid wetting agent to arrive at the composition of the granular materials distributed onto the field. The apparatus assures uniform and controllable introduction of each component into the distribution system.